This is a competing renewal application for a NIDA Mentored Clinical Scientists Development Program Award in Drug Abuse and Addiction (K12; PAR-07-346). The applicant Institution is the American Academy of Child and Adolescent Psychiatry (AACAP) under the leadership of Dr. Paula Riggs (Program Director/Principal Investigator). The majority of psychiatric and substance use disorders (SUD) begin during childhood or adolescence. Although the co-occurrence of psychiatric and substance use disorders is extremely common, the Institute of Medicine (2003) has identified a critical shortage of child and adolescent psychiatrists with dual training in developmental psychopathology and addiction. This shortage has contributed to broad research gaps and a lack of empirically-supported prevention and treatment. To address these gaps and the aims of this Initiative, we propose to support the career development of six child and adolescent psychiatrists who are committed to research independence in clinically relevant areas of drug abuse and addiction. In order to accomplish this aim, it will be necessary to expand the network of senior investigators and addiction research centers and training opportunities for young investigators, which is the second aim of the Initiative. During two previous funding periods from 1998-2004 (Leventhal.Pl) and 2005-2009 (Riggs, PI), the AACAP Physician Scientist Program in Substance Abuse (K12) has significantly increased the number of child and adolescent psychiatrists with addiction research careers and expanded the network of mentors and addiction research training centers by partnering with NIDA's Clinical Trials Network as a training platform for the AACAP K12. The commitment, environment and resources of the AACAP make it an ideal institutional home for the K12. With more than 90% of the child and adolescent psychiatrists in the country as members, the AACAP is well-positioned to facilitate the speed at which research is translated into practice. If funded, we propose to continue building on the success of our two previous AACAP K12 Awards to address the aims of this NIDA Initiative.